what is the point of telling add_filter how many parameters you want passed to the function?

The reason is that you can register native PHP functions as callbacks. Passing more parameters to them then they expect will raise a warning.

Imagine a filter that can pass 6 parameters and trim() as callback. PHP would now raise an error:

Warning: Wrong parameter count for trim() in …

Some custom callbacks might also change their behavior depending on the amount of passed arguments. That’s surely not good code, but such code exists, and it would break if WP would change its current behavior now.

Related Posts:

  1. Where is the best place to use add_filter
  2. Edit plugin without hooks in functions.php
  3. Using add_filter inside another class
  4. How to list the Hooks and order of execution in current loading page? [duplicate]
  5. Pass A Value From Outside To A Plugin Variable
  6. Failed to invoke other hook from the init hook
  7. How can I filter blog name?
  8. Custom preview_post_link not working for draft post
  9. Add Fields with Sub-Fields to WP Job Manager
  10. Determine plugin name from within plugin_action_links filter
  11. merging an array to an existing array using add_filter
  12. Creating a plugin to sanitize comment and the url field before display only
  13. How to find the origin of a file upload from within wp_handle_upload?
  14. White page by using filter template_include
  15. How to check current user before all actions and filters?
  16. Create a navbar filter that filters by a custom field
  17. Passing an array from shortcode-function to filter-function
  18. Get Time Taken By Each Action Hook in WordPress
  19. qTranslate remove default directory from link
  20. How to change the name of the “edit my profile” link in the WordPress admin backend
  21. Proper way to replace the_content only for pages created by custom plugin
  22. add_filter doesn’t work
  23. Redirect to another page using contact form 7? [closed]
  24. Check if variable is set in filter
  25. Check filter defined or not?
  26. Add a function call after content automatically?
  27. How to add filter for wordpress plugin?
  28. How to use add_action for multiple instances of the same class
  29. How to append new form elements in “Add New” form of Users in WordPress admin panel?
  30. Want to create custom design of progress indicator in wpforms
  31. Add hook after content without formatting
  32. Using OR Condition with facetwp facets
  33. 500 Internal server error wp_handle_upload_prefilter
  34. Nested Actions and Filters
  35. Remove action added in plugin class from theme
  36. Using multi-dimensional array with filter
  37. Can I add content before post content without using the_content filter
  38. WordPress Add advertising ads befor and after content with periority [closed]
  39. trying to create simple plugin to filter categories from all authors
  40. shortcode which is introduced into entry the blog, and appears in side bar
  41. How do i get all author posts on custom post type list
  42. Unable to pass arguments from plugin form to filter hook using ajax, the data is transferring via ajax but unable to pass as arguments in filter hooks
  43. Get a list of all registered actions
  44. Update plugin from personal API
  45. Where the Nickname is being used in WordPress
  46. WordPress apply_filters() Arguments Missing
  47. How can I include a setting that has a variable number of values in a settings page using register_setting?
  48. How to prepend to the_title for admin-side plugin’s use
  49. Adding dynamic section to WordPress
  50. Custom data-id wp_enqueue_script
  51. plugin_action_links_{$plugin_file} hook not in the main plugin file
  52. Creating search filter through plugin
  53. Yoast SEO blocking/re-initialising longer running process
  54. template_redirect not being called when using ajax
  55. Is there a way to alter the order in which the plugins appear in the page?
  56. How to correctly detect accessing wp-content/uploads?
  57. Get IDs of Images from Gallery Block in InnerBlocks of a Custom Gutenberg Block
  58. WordPress plugin – Error “Plugin generate 2890 characters of unexpected output when activated”
  59. Change plugin main file name (that is currently in the repo)
  60. Edit Yoast SEO breadcrumbs output [closed]
  61. Using a post-signup hook to get user details
  62. How to remove plugin metaboxes from edit.php
  63. Suggestions on Approach to New Plugin I’m Stuck On
  64. Insert Array in Plugin Database
  65. plugin wraps the entire content
  66. Shortcode Attributes to Return different $_POST
  67. How do I change where a plugin pulls updates from?
  68. How programatically cause uploads folder to be created?
  69. How to get a notification when the plugin is installed?
  70. WordPress Post HTML after Posting
  71. Settings options not showing up on Sub Menu page in WordPress plugin
  72. Filtered content appears in the excerpt
  73. unregister a sidebar widget
  74. Custom Meta box change size
  75. Could add_query_arg() redirect user to external site?
  76. Use a hook or filter, or overwrite this Gamipress function?
  77. The Build menu theme is frozen with the wordpress theme
  78. what functions to use to resize images and create DB metadata for them after/during upload?
  79. How to prevent redoing get_posts queries and make results available to other scripts?
  80. Prefix WordPress Taxonomy Tags With Hashtag Symbol Like Twitter
  81. Change Woo Custom Endpoint Titles from a Plugin
  82. WP internationalization not loaded
  83. Adding custom cron_schedule prior to wp_schedule_event
  84. Create plugin with form in post and submit it to specific form
  85. Storing values in Post Meta vs new tables
  86. Get page type to display content
  87. Widget redirecting to home page
  88. Capturing POST data
  89. How to add different CSS for galleries
  90. I am using multi image metabox plugin but I did get how to display the images in templete?
  91. How to open author url linked to a new tab in settings page in the WordPress plugin list
  92. How can I properly sanitize the update_option in WordPress?
  93. Why is my menu page not being displayed?
  94. Suitable hook when creating, updating and deleting posts programmatically
  95. How to add product thumbnail on orders list on backend?
  96. How can I gather forums posted by visitors from different sites in one place? [duplicate]
  97. How to make content as required in custom post type?
  98. How to create a “Most Popular” & “Latest” TAB in WordPress
  99. is_user_logged_in() undefined at shutdown in plugin context
  100. What are Seeds? [closed]